= 987654321

22. 1 x 8 + 1 = 9; 12 x 8 + 2 = 98; 123 x 8 + 3 = 987; 1234 x 8 + 4 = 9876; 


12345 x 8 + 5 = 98765; 123456 x 8 + 6 = 987654; 1234567 x 8 + 7 = 9876543;


 12345678 x 8 + 8 = 98765432; 123456789 x 8 + 9


 = 987654321